If you want to find what became of Pelagia/Blanche, you may have to do some digging.
Here is John and Blanche Hasenfus in the 1940 census, with daughters Florence and Violet:
https://familysearch.org/ark:/61903/3:1:3QS7-L9MY-35H?mode=g&cc=2000219.
The 1930 census has Blanche as a naturalized citizen. Since she remarried in 1921, she likely got her naturalization through marriage to an American citizen. I couldn't find a naturalization for her in the FamilySearch.org Eastern Pennsylvania Naturalizations (where a record would logically be), so that seems to confirm her getting it through marriage.
You might look on Ancestry for a Pennsylvania death certificate (certificates up to 1963, I think, are on Ancestry) for Pelagia/Blanche under the various combinations of her names (including alternate spellings in English of the Polish original).
Daughters Florence and Violet are not in any of the Pennsylvania marriage records on FamilySearch.com (there are three or four separate databases for Pennsylvania marriages). They may have married after the period covered by the databases--1950 was the latest cutoff. The Register of Wills for Philadelphia County may have records if they married in Pennsylvania. There is also the possibility that the daughters married in New Jersey, which is only across the Delaware River.
Regards,
John
